Apparatus for dry spinning artificial fibers



Aug. 11, 1953 e. CURTIS APPARATUS FOR DRY SPINNING ARTIFICIAL. FIBERS 2 Sheets-Sheet 1 Filed April 1, 1952 4 //2ve/7f 0r Geoffrey Cuff/s By his aflomeys Aug. 11, 1953 e. CURTIS APPARATUS FOR DRY SPINNING ARTIFICIAL FIBERS 2 Sheets-Sheet 2 Filed April 1, 1952 /m/enf0 Geoffrey Curf/s' By his attorneys Patented Aug. 11, 1953 APPARATUS FOR DRY SPINNING ARTIFICIAL FIBERS Geofl'rey Curtis, Coventry, England, assignor to Courtaulds Limited, London, England, a British company Application April 1, 1952, Serial No. 279,901 In Great Britain May 22, 1951 Claims.

This invention relates to apparatus for dry spinning artificial fibres, for example of cellulose esters and ethers.

In the commercial production of cellulose acetate threads by dry spinning, a solution of the cellulose acetate in a volatile solvent, usually acetone, is extruded through a jet mounted in the top of a long spinning cell containing a heated gas to remove the volatile solvent. Such spinning cells are normally of the order of feet long and are arranged in groups side by side so that the heated gases of the evaporative atmosphere can be continuously circulated throughout the groups of cells. With existing circulating systerns the heat requirements are high and costly, and in addition an appreciable quantity of heat is usually lost into the atmosphere of the spinning room which thereby tends to become uncomfortable and oppressive to the operatives. It has previously been proposed, for example in United States Patent specification No. 2,145,290, to use shorter spinning cells up to 14 inches in length, but such proposals have generally required a long air path for the thread after it has emerged from the cell.

The object of the present invention is to provide an improved circulatory system for the heated gases which permits adequate solvent removal within short spinning cells.

According to the present invention, apparatus for dry spinning artificial fibres comprises in combination a group of spinning cells, preferably each less than 24 inches in height and a circulatory system for the heated gases of the evaporative atmosphere which includes a common supply trunk and a common return trunk, at least half of the lower end of each spinning cell being suspended within the supply trunk and each spinning cell having a direct connection with the return trunk.

In a preferred form of the invention one or more heaters for the gases of the evaporative atmosphere are so arranged that a substantial part of the heated gases surrounding any one spinning cell has been circulated around not more than three other cells since leaving the heater. The machine may have two parallel rows of spinning cells with a supply trunk for each row, a common return trunk and a central conduit above the return trunk containing heaters for the gas of the evaporative atmosphere, preferably so arranged that there is one heater for each set of four cells of each row.

The circulatory system includes provision for withdrawing part of the heated gases for recovery of the volatile solvent and replacing it with fresh gas.

Adjustable baflles for throttling the gases at each spinning cell may be fitted between the supply trunk and a compartment providing the connection between the cell and the return trunk. Such bafiles enable the cell temperatures to be adjusted individually. Holes may also be provided within the spinning cell so that some of the gases can pass direct from the supply trunk into the spinning cell. In this manner the temperature at the spinning jets may beraised without increasing the amount of air tapped off for solvent recovery purposes.

The invention as applied to a sixteen end machine is illustrated by way of example in the accompanying drawings in which:

Figure 1 is a vertical section through the machine,

Figure 2 is a fragmentary section on the line 2-2 of Figure 1,

Figure 3 shows a variation in which adjustable bafiles are provided for throttling the air at the spinning cell, and Figure 4 shows a further variation in which holes are provided in the spinning cell.

The machine shown in Figures 1 and 2 of the drawings has sixteen spinning cells I, the spinning solution being extruded through a jet 2; the thread so formed passes vertically downwards and is withdrawn from the cell through a slot in the door 3 for processing and collection in the usual manner.

The cells I are arranged in two rows of eight cells each and are divided by a conduit 4, housing two heaters 5. The evaporative atmosphere is drawn by a fan 6 and divided into two streams; as shown in Figure 2 each gas stream passes over one of the heaters 5, and the heated gases are passed into supply trunks I to heat the cells I and are then passed by way of a common return trunk 8 back to the heaters 5. As shown particularly in Figure 1 just over half of each spinning cell I is suspended within one of the supply trunks I and each cell is directly connected to the return trunk 8. In order to assist in the maintenance of uniform air circulation to each cell I, a restriction I2 is provided in the supply trunk I and a. compartment I3 which provides the connection between the cell I and the return trunk 8. Part of the heated gases is continuously tapped oil through pipes 9 leading from the cells I to a single pipe III connected to a solvent recovery plant (not shown), the gases so removed being made up by drawing in fresh gas through ports II.

jets 2 without increasing the amount of air tapped off through the pipes 9 for solvent recovery-p111".- poses.

What I claim is:

l. Apparatus for dry spinning artificial fibres comprising in combination, a group of spinning cells each not greater than 24 inches in height,

a circulatory system for the heated gases of theevaporative atmosphere comprising at-least one heater for the gases, a supply trunk and a common return trunk for the heated gases, at least one half of each spinning cell, being positioned within the supply trunk and each spinning cell having a direct connection with the return trunk, means communicating within the spinning cells for withdrawing part of the heatedgases for sol,- vent recovery, and at, least one. port in the return trunk for drawing in fresh gases to replace the gases drawn off for solvent, recovery.

2. Apparatus for dry spinning artificial fibres comprising in combination, a group of spinning cells each not greater than 24 inchesin height and arranged in two parallelrows, a circulatory system for the heated gases of the evaporative atmosphere comprising a supply trunk for each row of cells, a. single common return trunk, a

central conduit above the return trunk leading into both supply trunks, at least one heater in the conduit for heating the gases of the evapo rative atmosphere, at least one half of each spinning cell being positioned within a supply trunk and each spinning cell having a direct connection with the return trunk, means communicating with the spinning cells for withdrawing part of the heated gases for solvent recovery, and at least one port in the return trunk for drawing in fresh gasesrto replace the gases drawn off for solvent recovery.

3. Apparatus as claimed in claim 2 wherein one heater is provided for each set of four cells of each row.

4. Apparatus as claimed in claim 2 wherein a compartment provides the connection between the cell and the return trunk and adjustable battles for throttling the gases are fitted to each cell between the supply trunk and said compartment.

5. Apparatus as claimed in claim 2 wherein holes are provided in the portion of the spinning cell within the supply trunk so that some of the gases can pass direct from the supply trunk into the spinning cell.

GEOFFREY CURTIS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,145,290 Bower Jan. 31 1939 2,351,772 Lodge June 20, 1944 2,515,393 Burke July 18; 1950 

